1. Field of the Invention
This application relates to a novel steerable wheeled pushcart suitable for use as a child's toy. More particularly, it relates to such a pushcart having an improved steering mechanism that is safer and more reliable in operation than prior pushcart steering mechanisms.
2. Description of the Prior Art
The concept of a steerable, two-wheeled toy pushcart is known in the art. For example, such a pushcart is shown in U.S. Pat. No. 1,681,876, issued Aug. 21, 1928 to Peterson. However, the steering mechanism shown in that patent has significant safety hazards for children, with its exposed springs and scissors type of relative movement between the transverse axle and the steering handle, which create pinch and mash hazards. The relationship among the transverse axle, steering handle and springs in that pushcart also significantly limit design flexibility. If it is desired to cover the springs and therefore eliminate the pinching hazard associated with them, there is little variation possible in the configuration of the pushcart body. If the steering handle attachment is moved rearward on the pushcart body, the result is a tendency of the pushcart to jacknife. If the axle is moved rearward on the pushcart body, this results in an excessive forward bobbing of the pushcart body front end during turns. The resulting body to ground clearance reduction may produce a further safety hazard with sudden stoppage of forward motion.
Additional problems with the steering mechanism in that pushcart include warping of the diverging steering bars in their lateral plane when torsional steering forces are applied to them and gimbal locking of the steering mechanism when the king bolt has its longitudinal axis perpendicular to the ground. Increasing steering force is required as the steering handle is lowered, raising the king bolt toward the perpendicular position. This increased steering force accentuates the warping of the steering bars. A further pinch hazard exists at the prop-to-steering handle attachment point. Additionally, steering limits are not provided for and their presence in this design would create another mash or pinch hazard.
A similar design for a steerable, two wheeled pushcart is shown in Kounovsky, U.S. Pat. No. 1,097,102, issued May 19, 1914. That design is not capable of mimicking the self steering action of a car or truck.
Another example of a steerable pushcart is shown in U.S. Pat. No. 1,310,651, issued July 22, 1919 to De Long. In that design, a four wheeled pushcart has a steering handle connected to pivot the front wheels of the cart for steering. A four wheeled steerable toy vehicle similar to this design is commercially available from Sears under the designation Nylint "Steer Crazy" pickup.
An example of a self centering mechanism for a tilting platform type of roller skate is disclosed in Hanson, U.S. Pat. No. 321,434, issued July 7, 1985. However, that mechanism is not used with a vehicle having a steering handle, nor does the patent suggest such a usage.
Other examples of steerable pushcarts and similar devices are shown in the following issued U.S. patents: U.S. Pat. No. 1,446,140, issued Feb. 20, 1923 to Weber; U.S. Pat. No. 2,021,814, issued Nov. 19, 1935 to Stinson et al.; U.S. Pat. No. 2,800,337, issued July 23, 1957 to Avril; U.S. Pat. No. 2,859,975, issued Nov. 11, 1958 to Weaver et al.; U.S. Pat. No. 2,950,121, issued Aug. 23, 1960 to Fisher and U.S. Pat. No. 3,066,945, issued Dec. 4, 1962 to Prescott. Despite the many examples of such devices, a satisfactory solution to the problems associated with a steerable pushcart of the type disclosed in the Peterson patent is not available in the prior art.
While a wide variety of such pushcart designs are known in the prior art, a steering mechanism that will operate satisfactorily with either a two wheeled or a four wheeled pushcart has not been provided. In particular, there is no steering mechanism that will provide controllable steering of the front wheels of a four wheeled pushcart when all four wheels are on the ground and with the rear wheels when the front wheels are raised from the ground.